Telephone system



E. S. PETERSON TELEPHONE SYSTEM Dec. 3, 1935.

Filed July 12, 1934 2 Sheets-Sheet 1 INVENTOR EDWARD S. PETERSON 7 mm DEE. 3, 1935. E. E. PETERSON 2,623,249

TELEPHONE SYSTEM Filed July 12, 1934 2 Sheets-Sheet 2 REMOTE OPERATING CENTER T U I I "r A f; EL 1 I E II T I D S L E I N E 9 a T INVENTOR EDWARD S. PETERSON Patented Dec. 3, 1935 UNITED STATES TELEPHONE SYSTEM Edward S. Peterson, Elmwood Park, Ill., assignor to Associated Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application July 12, 1934, Serial No. 734,747

9 Claims.

The present invention relates to telephone systems in general, but is concerned more particularly with semi-automatic telephone systems whereby connections between manual lines entering an exchange may be set up by automatic switches under the control of an operator at a switchboard in a remote exchange.

In system of this type connections are set up between manual magneto lines by automatic switching apparatus responsive to control exercised over a control trunk extending between the manual magneto exchange and a remote operating center and was designed to improve service in rural communities by making it possible for a remote operator, instead of a local operator, to control the connections. The remote operator can give practically the same service to the local subscribers as could the local operator and can give the service in very much the same manner, the chief difference being that she operates a dial instead of plugging up cords. This equipment is intended to replace manual magneto switchboards which cannot profitably carry the cost of a local operator. Systems of the foregoing type are commonly known as remotely controlled .exchanges and generally referred to as R. C. X.s.

The main object of the present invention is the provision of a distributor circuit for operat ing two remotely controlled exchanges, or R. C. X.s, over a single control trunk extending to a remote operating center.

One feature of the invention relates to the means whereby the control trunk is made busy during the establishment of a connection in one of the R. C. X.s to prevent a 'call from the other R. C. X from interfering therewith.

Another feature of the invention relates to the means whereby calls waiting in both R. C. Xs alternately take the control trunk into use.

Other features of the invention will be apparent from the following decription of the accompanying drawings comprising Figs. 1 and 2.

Referring now to Fig. l: the upper left-hand corner diagrammatically represents one of the R. C. X.s, or R. C. X. #1 and the lower left-hand corner diagrammatically represents the other R. C. X. or R. C. X. #2. The detail circuits of R. C. X. #1 and R. C. X. #2 are fully disclosed and described in a copending application, S. N. 676,439, filed June 19, 1933. The reference characters in the instant application correspond to the reference characters shown in Fig. 5 of such copending application. R. C. X. #1 is connected to the distributor circuit by way of conductors l and 452, while R. C. X. #2 is connected by way of the dotted conductors 45l and 452.

The right-hand portion of Fig. l and the lefthand portion of Fig. 2 show the relays and circuits of the distributor circuit which extends by way of conductors 453 and 454 to the remote operating center shown at the right of Fig. 2.

Switch S in Fig. 1 indicates a so-called minor switch having a rotary magnet, Rot. Mag, for stepping wiper 90 one step upon each energization, and a release magnet, Rls. Mag, for restoring the wiper to its normal position. Off normal springs ON are normally open when wiper 90 is in normal position and close when the wiper moves off normal.

The equipment located at the remote operating center comprises the usual operators head set, drop, calling device C. D., repeating coil RC2, and the ringing, monitoring and connecting keys. This equipment is identical to that shown in Fig. 5 in the copending application. By a comparison between the copending and instant applications it can readily be seen that the distributor circuit is inserted in the control trunk between the remote operating center and the two R. C. X.s, such distributor circuit being preferably located at the R. C. X. closest to the operating center.

The general operation is as follows: A local subscriber in one of the R. C. X.s, upon initiating a call by turning his hand generator, causes a finder in such local exchange to find his line and operate certain relays in the distributor circuit, if idle, to signal the remote operators over a the control trunk extending to the remote operating center. The remote operator answers the call, dials back over the same control trunk and distributor branch to operate automatic switches, in the local calling R. C. X. to establish the desired local connection between the local calling and local called lines. After ringing the called party the remote operator then retires from the local connection and the distributor circuit and control trunk is then made available for other calls from both R. C. X.s. Either the local calling or called line can release the local connection by turning the hand generator.

Having given a general description of the system and drawings, a detailed description of the circuit operations will now be given.

For this purpose it will be assumed that one of the regular magneto subscribers served by R. C. X. #1 wishes to be connected with another local subscriber whose line also terminates in the ame R. C. X. The calling subscriber operates his hand generator in the usual manner, projecting ringing current over his line to operate and lock the line relay at the exchange. In response to the operation of the line relay a finder in the local exchange hunts for and finds the calling line. In response to the finder finding the calling line ground is momentarily connected to a slow-to-release relay 430. The foregoing detail circuit operations up this point are described in detail in the aforesaid copending application.

Relay 430 is momentarily operated and at armatures 432 and 48! completes a circuit for en ergizing relay 20 as follows: from ground by way of working contact and armature 432, conductor 45! armature 42 and resting contact, lower winding of relay 20, conductor 452, armature 48! and working contact, and through the resistance to grounded battery. At armature 2! relay 20 temporarily completes a locking circuit for itself by way of armature 4! and resting contact through its upper winding and at armature 22 completes a circuit for energizing relay 4!! in case the distributor circuit and control trunk is not in use. The circuit for relay 40 extends from grounded armature 22, armatures 35 and 6! and through the lower winding of relay 40 to grounded battery. At armature 4! relay 4!] opens the looking circuit of relay 20 and grounds conductor 9| to complete the energizing circuit for slow to energize relay I 50. At the resting contact of armature 42 relay 40 opens a point in the original energizing circuit of relay 2!! and at the working contacts of armatures 42 and 43 prepares points in the talking circuit between R. C. X. #1 and the control trunk. At armature 44 relay 40 completes a locking circuit for itself as follows: from ground by way of armatures 63, 34, and 44 through its upper winding to grounded battery. Armature 44 also connects this same ground to the second or #2 contact accessible to wiper 90 of which S. At armature 45 relay 40 opens a point in the energizing circuit of relay 30 to prevent its energization in case relay I0 is energized on a call from R. C. X. #2. At armature 46 relay 40 opens a point in the locking circuit of relay 3!! and at armature 4! completes an energizing circuit for slow to operate relay I as follows: from grounded armature T3 and resting contact, armatures 64 and 41, conductor 99, normally closed springs controlled by armature I4! and through the winding of relay I60 to battery.

Relay 29 deenergizes in response to the operation of relay 40 and at armature 22 opens a point in the original energizing circuit of relay 40 which, however, is locked energized. Relay I60, upon energizing over the above traced circuit, at armatures I6! and I62 and their working contacts connects ground and battery to conductors 454 and 453 to operate the drop at the remote operating center and at armature I63 completes an obvious circuit for energizing slow to operate relay I 40. The circuit for operating the drop at the remote operating center may be traced as follows: from ground by way of working contact of armature I6! and said armature, control trunk conductor 454, upper left-hand winding of repeating coil RC2, spring 46!, and resting contact of key K, winding of drop, lower left-hand winding of repeating coil RC2, control trunk conductor 453, armature I62 and working contact, and through the resistance to groundedbattery.

Relay I50, upon energizing, at the resting contacts of armatures I5! and I52 disconnects relay I30 from the control trunk conductors and at their working contacts prepares a point in the talking circuit. At armature I53 relay I50 opens a point in the impulsing circuit to relay I20 and rotary magnet Rot. Mag. After an interval slow to operate relay I40 energizes and at armature I4! completes a locking circuit for itself from grounded conductor 99 as well as opening the circuit to relay I60 and the normally closed springs controlled by armature I 4!.

Relay I60, upon deenergizing, at armature I63 opens the original energizing circuit of relay I40 and at armatures I6! and I62 disconnects ground and battery from the control trunk and connects the control trunk conductors 454 and 453 to conductors 92 and 93.

When the operator at the remote operating center observes the operation of the drop at her position indicating a call, she will operate the key K which at springs 460 and 464 connects her head set to the right-hand windings of repeating coil RC2 to complete the talking circuit to the calling subscriber. The talking circuit to the calling subscriber may be traced as follows: from the calling subscribers line to conductors 268 and. 269, winding of repeating coil RCI, resting contacts of armatures 432 and 48! and said armatures, conductors 45! and 452, armatures 42 and 43 and their working contacts, through the condensers CI and C2, conductors 92 and 93, working contacts and armatures I5! and I52, resting contacts and armatures I6! and I62, and control trunk conductors 454 and 453 to the left-hand windings of repeating coil RC2. At spring 46! and its resting contact the circuit for operating the drop is opened and at the make springs on springs 46!, 462 and 463 ground through the impulse springs of the calling device CD is connected to both trunk conductors 454 and 453 through the left-hand windings of repeating coil RC2. A circuit may now be traced for energizing relay and the line relay 302 in the common equipment of the copending application as follows: from ground the impulse springs of the calling device CD, springs 463, normally closed springs of the negative ring key, working contacts and spring 46!, upper left-hand winding of repeating coil RC2, conductor 454, armature I6! and resting contact, armature I5! and working contact, conductor 92, winding of relay 80, working contact and armature 42, conductor 45!, .armature 432 and resting contact, upper right-hand winding of repeating coil RCI, conductor 210 and through the winding of the line relay in the common equipment to grounded battery. At the same time another circuit may be traced for energizing relay 50 in series with relays 303 and 304 shown in the common equipment in the copending application as follows: from ground through the impulse springs of the calling device CD, springs 463, springs of monitor key MK, normally closed springs of the positive ring key, springs 462, lower left-hand winding of repeating coil RC2, conductor 453, armature I62 and resting contact, armature I52 and working contact, conductor 93, winding of relay 56, armature 43, conductor 452, armature 48! and resting contact, lower right-hand winding of repeating coil RCI, conductor 21! and through the windings of relays 363 and 304 in R. C. X. #1 to grounded battery. A branch of this circuit extends through the winding of relay I!!! to grounded battery for energizing this relay which F at armature I I! grounds conductor 94 to energize relay I0.

Relays 50 and 80, upon energizing, at their armatures 5! and 8! completes an obvious circuit for energizing slow to release relay I0. At armature H relay 1U prepares a point in the impulsing circuit previously opened atv armature I53, at armature l2 and resting contact opens a point in the release circuit to release magnet Rls. Mag. and at the working contact of armature 72 completes a circuit for energizing slow to release relay 60. At the working contact of armature l3 relay l0 maintains the locking circuit of relay l0 and at the resting contact thereof disconnects ground from conductor 99 to unlock relay Mil, which thereupon deenergizes. Relay 60, upon energizing, at armature 6! opens a further point in the original energizing circuit of relay 4!), at armature 52 opens a further point in the energizing circuit of relay 3G to prevent its energization, at armature 63 disconnects one of the multiple grounds from the locking circuit of relay 4% now grounded at armature i3, and at armature 84 opens a further point in the circuit for grounding conductor 99.

The operator now challenges the call and receives the number to be called. The operator now operates the calling device CD in accordance with the digits in the called number to operate the automatic switches R. C. X. #1 to complete the desired connection as described in the copending application. Relays 58, 86 and H6 follow the impulses but since relay W is a slow to release relay the same is maintained energized. The operator rings the called subscriber by the operation of either her negative ring key or positive ring key and monitors the connection, if desired, as described in the copending application. The operation of either ring key will open the oil'- cuit to either relay 5!! or 85 dependent upon the key operated but since one of such relays is energized relay It is maintained in energized position.

After the satisfactory completion of the desired local connection the control operator will disconnect from the connection by restoring the answer and dial key K. In response to the restoration of key K relays 50, 8G, and H361 deenergize and at armatures 5!, 8i and iii open the circuit to relay 10 which deenergizes after an interval. Relay 10, upon deenergizing, at armature 12 opens the circuit to relay 5% which deenergizes after an interval and at armature l3 opens the locking circuit of relay it which thereupon deenergizes. At armature ll relay to opens the circuit of relay I50, at armature 42 restores the original energizing circuit of relay 25, at armatures 42 and 43 disconnects the trunk conductors and 452, from conductors Q2 and 93, at armature 44 opens a point in its locking circuit, at armature 45 prepares a point in the energizing circuit of relay 38, at armature 45 prepares a point in the locking circuit of relay 3G, and at armature 41 opens a point in the circuit of relay I60. Relay I59, upon deenergizing, at armatures l5l and I52 disconnects conductors 92 and 93 from conductors 454 and 653 and connects the winding of relay I30 in place thereof. Relay 60, upon deenergizing, at armature 6i prepares the circuit for relay 4%, at armature 62 prepares a point in the circuit for relay 30, at armature 53 prepares a. point in the locking circuits of relays 3E! and iii], and at arinature 5 5 prepares a point in the circuit for relay 56. All relays have now been restored to their normal positions as shown in the drawings.

It will now be assumed that a regular magneto subscriber served by R. C. X. #2 wishes to be connected with another local subscriber whose line also terminates in this R. C. X. The calling subscriber operates his hand generator in the usual manner to initiate a call. In response to a call from R. C. X. #2 relay 438 is temporarily operated in a manner similar to that described for relay 430. At armatures 432' and 48l' ground and battery are temporarily connected to conductors 45V and 2-52 to complete an energizing circuit through the lower winding of relay I0 and armature 32. At armature H relay It] temporarily completes a locking circuit for itself through its upper winding and at armature l2 completes a circuit for energizing relay 30 as follows: from ground by way of armatures I2, 45 and 62 through the upper winding of relay 39 to grounded battery. In case the control trunk was in use then relay 39 and possibly relay may be operated with the result that relay 30 does not energize since the energizing circuit to relay 38 includes armatures 5 and 52. Relay 3!), upon energizing, at armature 3! and resting contact opens its locking circuit, at armature 3i and working contact grounds conductor 9! to energize slow to operate relay 156, at armature 32 and resting contact opens the original energizing circuit to the lower winding of relay H! to cause said relay to deenergize, at armatures 32 and 33 and their working contacts prepares points in the talking circuit over conductors 45! and 452, at armature 36 opens a point in the locking circuit of relay #8, at arm 35 opens a point in the energizing circuit of relay 4%), at armature 35 completes a locking circuit through its lower winding by way of armatures t5 and $3, and at armature 3? connects ground at armature 73 by way of armature 63 to conductor 99 to energize relay I60. In the same manner as previously described relays l5i3 and E60 and then relay Hi0 energize to transmit a calling signal to operate the drop at the operators position at the remote operating center.

When the operator observes the operation of the drop at her position she will operate the dial and answer key K to complete a talking circuit to the calling subscriber in R. C. X. #2. This circuit may be traced as follows: from the calling subscribers line, windings of repeating coil, resting contacts and armatures 532 and 48V, conductors 45! and 352, armatures 32 and 33 and working contacts, through the condensers Cl and C2, conductors 92 and 93, and thence over the previously traced circuit to the operators head set. A circuit may now be traced for energizing relay 8!) in series with the line relay in the common equipment in R. C. X. #2 as follows: from ground through the impulse springs of the calling device CD, springs 433, springs-of the negative ring key, springs 4 6i, upper left-hand winding of repeating coil RC2, conductor 454, armature it! and resting contact, armature i5! and working contact, conductor 92, winding of relay 80, working contact and armature 32, conductor 45!, armature 432' and resting contact, upper righthand winding of the repeating coil and through the winding of the line relay in the common equipment to grounded battery. At the same time another circuit is completed for energizing relay 58 in series with other relays in the common equipment as follows: from ground through the impulse springs of calling device CD, springs 463, springs of key MK, springs of positive ring key, lower left-hand winding of repeating coil RC2, conductor 153, armature I62 and resting contact, armature E52 and working contact, conductor 93, winding of relay 59, armature 33, conductor 452', armature 48V and resting contact,

and the lower right-hand winding of the repeating coil through the windings of the relays in the common equipment to grounded battery. A branch of this circuit extends through the winding of relay I I0 to grounded battery for energizing this relay which at armature I I I grounds conductor 94 for energizing relay 70. Relays 50 and 80 at their armatures 5| and BI also grounds conductor 94 to energize relay l0. Relay I0 and then relay 60 energize causing the deenergization of relay I40 as previously described. Relay I0 maintains relay 30 locked energized at armature I3.

The operator now challenges the call and receives the number to be called after which she operates the calling device CD in accordance therewith to operate the automatic switches in R. C. X. #2 to complete the desired connection as described in the copending application. After signalling the called subscriber and the satisfactory completion of the connection the control operator disconnects by restoring key K, whereupon relays 50, 80 and IIO and then relays I0 and 00 deenergize, as previously described. At armature I3 relay 19 opens the locking circuit of relay 30, which thereupon deenergizes. At armature 3I relay 30 opens the circuit of relay I50 which deenergizes, at armatures 32 and 33 disconnects the control trunk from conductors I and 452 as well as reestablishing the original energizing circuit for relay I0, at armature 34 prepares a point in the locking circuit of relay 40, and at armature 35 prepares a point in the energizing circuit of relay 40. All the relays are now restored to their normal positions and may be used on subsequent calls.

The foregoing description relates to normal operation at a time when the control trunk was not in use. It will now be assumed that a call is originated from R. C. X. #1 at the time the control trunk is in use in a call with R. C. X. #2, in which case relay 30 is energized. In response to the call relay 20 energizes and locks as before described but in this case does not complete an energizing circuit for relay 4% at armature 22 because relay 30 at armature 35 holds the circuit of relay 40 open. After the operator completes the call in R. C. X. #2 and disconnects relays 30 and B0 deenergize to complete the circuit for relay 40, whereupon the call is completed as previously described.

A similar arrangement is provided for energizing and locking relay I0 in case a call originates from R. C. S. #2 when the control trunk is in use on a call in R. C. X. #1. In this case relay I0 energizes and looks but cannot complete the circuit for relay 39 at armature I2 because relay 40 is energized. The call therefore waits until the control circuit is idle at which time the deenergization of relays 40 and 69 completes the circuit for relay 30 to allow the call to proceed as previously described. From the foregoing it can be seen that the control circuit is guarded when busy and that calls from the two R. C. X.s alternately take the control trunk into use when calls are waiting at both R. C. X.s.

In some instances the control operator may initiate a call either for testing purposes or for connecting to 2. called subscriber. In order to do this the operator actuates the key K at a time when the control trunk is idle, thereby connecting ground through the impulse springs of the calling device CD to trunk conductors 454 and 453, as previously described and this time armatures GI and 62 relay 60 opens the energizing circuits of relays 40 and 30 to prevent their energization.

The control operator now dials the digit 2 in case she desires to be connected with R. C. X. #1, or dials the digit 4 in case a connection with R. C. X. #2 is desired. Relay I30 deenergizes for each impulse and at armature I3I and resting contact completes the impulsing circuit for relay I20 and rotary magnet Rot. Mag. by way of conductor 95, armature II, conductor 96, armature I53, conductor 91, and through the winding of relay I20 and the winding of the rotary magnet in parallel to grounded battery. Relay 19, due to its slow releasing characteristics, does not deenergize during dialling. Relay I20, upon energizing, at armature I2I disconnects ground from conductor 98 and wiper 90 of switch S. Rot. Mag. energizes once for each impulse to step wiper 99 one step for each impulse received. Off normal springs ON close on the first step of wiper 90 to prepare the circuit to the release magnet Rls. Mag.

In case the operator dialled the digit 2 then wiper 90 comes to rest in engagement with its second bank contact to prepare a circuit for relay 40. Slow to release relay I20 deenergizes shortly after the impulsing period and at armature I2I completes a circuit for energizing relay 40, as follows: from grounded armature I2I, conductor 98, wiper 90, second bank contact, and through the upper winding of relay 40 to grounded battery. Relay 40, upon energizing, at armature 4| completes the circuit for energizing relay I and at armatures 42 and 43 connects conductors 45I and 452 to conductors 92 and 93. Relay I at armatures I5I and I52 disconnects relay I30 and connects conductors 454 and 453 to conductors 92 and 93, and at armature I53 opens the impulsing circuit. Relay I30 deenergizes and opens the circuit to relay I0 which, however, is maintained energized in response to the operation of relays 50, and H0 as a result of the connection being completed to R. C. X. #1 by relay 4 I50. The operation from here on is the same as previously described in the instant and copending applications. In this case, during the release of the connection relay "I0 at armature I2 completes the circuit for energizing the release magnet Rls. Mag. through the oil normal springs ON, thereby restoring the wiper to its normal position in which position o-lf normal spring ON opens the circuit to the release magnet.

In case the operator dialled the digit 4 instead of 2, then wiper 90 comes to rest in engagement with its fourth bank contact to prepare a circuit for relay 39. Relay I20 deenergizes after the dialling period and at armature I2I completes a circuit for energizing relay 30 as follows: from grounded armature I2I, conductor 98, Wiper 90, fourth bank contact, and through the lower winding of relay 39 to grounded battery. Relay 30, upon energizing, at armature 3| completes the switch S to normal.

energizing circuit of relay I50 and at armatures 32 and 33 connects conductors 34! and 452' to conductors 92 and 93. Relay I50, upon energizing, at armatures l5! and I52 disconnects relay I30 and connects conductors 92 and 93 to conductors 854' and 453. Relay I30 deenergizes, relays 50, 80, and IN energize, and the operation from here on is the same as previously described. During the release of the connection relay l closes the release circuit to Rls. Mag. to restore Having described the invention what is considered new and is desired to have protected by Letters Patent will be set forth in the following claims.

What is claimed is:

1. In a telephone system wherein an operator at a main exchange remote from a local exchange controls automatic switches in the local exchange over a common control trunk to complete direct connections between local subscribers lines, a second local exchange having automatic switches controlled over said control trunk to complete direct connections between local subscribers lines therein, two branches of said control trunk at said first local exchange, the first of said branches terminating in the first local exchange and the second branch terminating in the second local exchange, means in each branch at the first local exchange operated responsive to a subscriber in either local exchange initiating a call for seizing said trunk if idle by Way of its corresponding branch, and means responsive to said seizure for preventing the seizure of said trunk over the other branch and for automatically signalling the remote operator over said trunk.

2. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, a first and a second relay individual to each of said branches, means for energizing the first of said relays in response to a call over the corresponding branch, means responsive thereto for energizing the second of said relays in the corresponding branch in case the control trunk is idle, and means responsive to the energization of the second relay for seizing said control trunk and for automatically signalling the remote operator thereover.

3. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, a first and a second relay individual to each of said branches, means for energizing the first of said relays in response to' a call over the corresponding branch, means for locking said first relay energized in case the control trunk is busy over its other branch, means for energizing the second of said relays in the corresponding branch as soon as the control trunk becomes idle, and means responsive to the energization of the second relay for seizing the control trunk and for automatically signalling the remote operator thereover.

, 4. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, a first and a second relay individual to each of said branches, means for energizing the first of said relays in response to a call over the corresponding branch, means for locking said first relay in energized position, means responsive to the energization of said first relay for energizing the second of said relays in the corresponding branch in case said control trunk is idle, means for unlocking said first relay in response to the operation of said second relay, means for locking said second relay in energized position, means responsive to the operation of said second relay for connecting said corresponding branch to the control trunk, and means controlled by said second relay for automatically signalling the remote operator over said control trunk.

5. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, a first connecting relay for connecting the first exchange to said control trunk by way of said first branch, a second connecting relay for connecting the second exchange to said control trunk by way of said second branch, and operator controlled means controlled over said control trunk from the operators position for selectively operating either of said connecting relays to operatively connect the control trunk to the desired exchange.

6. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, means responsive to a call in either one of said exchanges for transmitting a signal over its corresponding branch, means in said branches operated in response to said transmitted signal, and means operated in response to the operation of said last means for repeating said signal to signal the remote operator over said control trunk.

7. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, means responsive to a call in either one of said exchanges for transmitting a signal over its corresponding branch, means in said branches operated in response to said transmitted signal, branch connecting means operated in response to the operation of said last means in case the control trunk is idle or thereafter operated as soon as the control trunk becomes idle to connect the control trunk to the calling exchange, and means operated in response to the operation of either of said branch connecting means for repeating said signal to signal the remote operator over said control trunk.

8. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and, the second of said branches extending to said second exchange, a first connecting. relay for connecting the first exchange to said control trunk by way of said first branch, a second connecting relay for connecting the second exchange to said control trunk by way of said second branch, subscriber controlled means in the first exchange for operating said first connecting relay to connect the control trunk to said first exchange by way of said first branch in case the control trunk is idle, subscriber controlled means in the second exchange for operating the second connecting relay to connect the control trunk to said second exchange by way of said second branch in case the control trunk is idle, and operator controlled means controlled over said control trunk for selectively operating either of said connecting relays to operatively connect the control trunk to the desired exchange.

9. In a telephone system, a first exchange, a second exchange, a control trunk extending from a remote operators position and terminating in two branches, the first of said branches extending to said first exchange and the second of said branches extending to said second exchange, a

control trunk to said second exchange bylway' of said second branch in case the control trunk is idle, means for preventing the operation of either connecting relay in case the other connecting relay is operated, and operator controlled means controlled over said control trunk for selectively operating either of said connecting relays to operatively connect the control trunk to the desired exchange.

EDWARD S. PETERSON. 

